Citrix NetScaler Authentication Bypass Using an Alternate Path or Channel
What to do
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
CISA deadline 2026-09-12 · due in 2 days · applies to US federal civilian agencies; used elsewhere as a reference SLA
What happened
Citrix NetScaler ADC and NetScaler Gateway contain an authentication-bypass vulnerability involving an alternate path or channel. When the NetScaler appliance is configured as an AAA virtual server or as a Gateway (SSL VPN, ICA Proxy, CVPN, or RDP Proxy), an unauthenticated remote threat actor may be able to bypass authentication.
Who is affected
Citrix NetScaler. Affected version ranges are listed in the vendor advisory and the NVD entry linked under Sources.
Weakness class: CWE-288.
Timeline
- Added to CISA KEVExploitation in the wild confirmed by CISA
- CISA remediation deadlinedue in 2 days
Sources
- NVD entry for CVE-2026-19490 nvd.nist.gov/vuln/detail/CVE-2026-19490
- CISA Known Exploited Vulnerabilities catalog www.cisa.gov/known-exploited-vulnerabilities-catalog
- support.citrix.com support.citrix.com/external/article/CTX696939/netscaler-adc-and-netscaler-gateway-secu.html
- cisa.gov www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- cisa.gov www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- nvd.nist.gov nvd.nist.gov/vuln/detail/CVE-2026-19490